If the plan of this book is not evident from the table of contents, it is as follows: An analysis was made of the chemical industries and the features essential to most of them selected for description. In this description the attempt was made to throw into prominence the basic principles, usually ending the section with a number of specific industrial applications, preferably in varied lines. The minor processes incidental or even essential to a single industry are not mentioned—there is, for example, nothing on bating for the practical tanner, nor on the production of pulp for1 the papermaker, though this process enters some other industries also. Where to draw the line even on what was touched was another problem. This is distinctly not an elementary text-book and a general knowledge of chemistry and mathematics is presupposed. On the other hand it is not a chemical encyclopedia, and anything that stops short of being a chemical Britannica will call down some wrathful queries as to why certain important facts were left out and why minor ones were put in. One may as well own up immediately that it was bad judgment as to the latter, and plead the publisher's unwillingness to put more white paper into the book for the former. The introduction of the matter on rare gases, radio-elements, etc., is to be justified by the newness of these subjects, and consequent lack of general knowledge concerning them. The matter of the multiplicity of contributors needs no great explanation, for we are all used to this in the modern handbooks. I believe it is a common saying that Helmholtz was the last universal genius, and we are fast arriving at the point where even a single subject becomes too vast for one man. At any rate, whether or not any of my learned confreres could write an entire chemical engineering handbook, I could not—hence the present form. I have tried not to edit the individuality out of these contributions, for I think the reader wants the writer's personality:—besides, some of the contributors are large, determined, aggressive men and it wouldn't have been safe.
As to acknowledgment of indebtedness, apart from the self-evident one to the contributors, I wish especially to thank Dr. Edward Weston, E. A. C. Smith, W. Y. Westervelt, H. C. Parmelee and Percy Barbour, apart from the last's evident work as contributor, though probably no friend of mine has escaped being' asked for advice on this book in the last two years.
And so, with much misgiving, this book is sent forth with the hope that chemical engineers in all lines may find something of profit in the general principles laid down, and this whether they be of the old school whose education dealt with atoms, or those of the very newest, who daily sup with electrons, or whether they be of the unhappy transitional epoch (in which stratum belongs the author) when no one fully believed the old, and no one understood the new.
NEW YORK, N. Y. DONALD M. LIDDBLL.